quite literally the major reason everyone uses wordpress is because of the available plugins, I help people make thousands online with their online stores thanks to free and paid plugins, if these same plugins were available in other cms platforms I would not be using wordpress, period.
therefore all forks will fail to gain any traction if the plugin situation isn't solved because wordpress today is the plugins. A sucessfull fork (besides having to be backed by a few millions) will put 80% of its focus on plugins and on attracting young developers, also wouldn't hurt to fund php and make it cool again.